"I'll go with you." He knows what he's supposed to say. The only problem is that what he wants to say doesn't match it. SPOILERS for DH / DHpt2.
Hermione had known as soon as the three of them were asked that she'd be going back to Hogwarts alone for her seventh year.
GHr. It didn't begin as an accident, or a conscious decision. So perhaps – against every other "perhaps" – it would end well.